This masterpiece of Renaissance metalwork is signed on the browplate by Filippo Negroli, whose embossed armor was praised by sixteenth-century writers as "miraculous" and deserving "immortal merit." Formed of one plate of steel and patinated to look like bronze, the bowl is raised in high relief with motifs inspired by classical art. The graceful mermaidlike siren forming the helmet's comb holds a grimacing head of Medusa by the hair. The sides of the helmet are covered with acanthus scrolls inhabited by putti, a motif ultimately derived from ancient Roman sculpture and wall paintings.